Electrolyzer and method of use

Abstract

Provided herein are methods for operating carbon oxide (COx) reduction reactors (CRR) and related apparatus. In some embodiments, the methods involve shutting off, reducing, or otherwise controlling current during various operation stages including hydration, break-in, normal operation, planned shut-offs, and extended shutoff or storage periods.

What is claimed is: 
     
         1 . A method of operating a membrane electrode assembly (MEA) for CO x  reduction, the MEA comprising a cathode, an anode, and a membrane between the cathode and the anode, and the method comprising:
 generating a CO x  reduction product by applying a current density to the MEA and inletting a gas comprising CO x  to the cathode of the MEA to reduce CO x  and produce the CO x  reduction product; and   at intervals, reducing the applied current density from a first current density to a reduced level, wherein the applied current density is reduced from the first current density in multiple steps.   
     
     
         2 . The method of  claim 1 , further comprising, at each interval, after reducing the applied current density, increasing the applied current density to the first current density. 
     
     
         3 . The method of  claim 2 , wherein the applied current density is increased from the reduced level to the first current density in a single step. 
     
     
         4 . The method of  claim 1 , further comprising maintaining the applied current density at the reduced level for at least 5 microseconds. 
     
     
         5 . The method of  claim 1 , further comprising maintaining the applied current density at the reduced level for at least 500 microseconds. 
     
     
         6 . The method of  claim 1 , further comprising maintaining the applied current density at the reduced level between 500 microseconds and 10 minutes. 
     
     
         7 . The method of  claim 1 , wherein the reduced level is zero. 
     
     
         8 . The method of  claim 7 , wherein the MEA has an open circuit potential when the applied current density is zero. 
     
     
         9 . The method of  claim 8 , wherein a duration of the intervals between reducing the applied current density from the first current density to zero decreases at least once as an MEA operating time increases. 
     
     
         10 . A method of operating a membrane electrode assembly (MEA) for CO x  reduction, the MEA comprising a cathode, an anode, and a membrane between the cathode and the anode, and the method comprising:
 generating a CO x  reduction product by applying a current density to the MEA and inletting a gas comprising CO x  to the cathode of the MEA to reduce CO x  and produce the CO x  reduction product; and   at intervals, reducing the applied current density from a first current density to a reduced level, maintaining the applied current density at the reduced level for a duration of time, and increasing the applied current density from the reduced level to the first current density after the duration of time has elapsed, wherein reducing the applied current density from the first current density to the reduced level is characterized by a first current density vs. time profile, increasing the applied current density from the reduced level to the first current density is characterized by a second current density vs. time profile, and wherein the first current density vs. time profile and the second current density vs. time profile are asymmetric relative to one another.   
     
     
         11 . The method of  claim 10 , further comprising maintaining the applied current density at the reduced level for at least 5 microseconds. 
     
     
         12 . The method of  claim 10 , further comprising maintaining the applied current density at the reduced level for at least 500 microseconds. 
     
     
         13 . The method of  claim 10 , further comprising maintaining the applied current density at the reduced level between 500 microseconds and 10 minutes. 
     
     
         14 . The method of  claim 10 , wherein the reduced level is zero. 
     
     
         15 . The method of  claim 14 , wherein the MEA has an open circuit potential when the applied current density is zero. 
     
     
         16 . The method of  claim 10 , wherein the first current density vs. time profile is characterized by reducing the applied current density from the first current density to the reduced level in multiple steps. 
     
     
         17 . The method of  claim 1 , further comprising
 after reducing the applied current density, increasing the applied current density to the first current density, wherein reducing the applied current density from the first current density to the reduced level is characterized by a first current density vs. time profile, increasing the applied current density from the reduced level to the first current density is characterized by a second current density vs. time profile, and wherein the first current density vs. time profile and the second current density vs. time profile are asymmetric relative to one another.